Figure 5.

GH Is One of the Paracrine Signals that Increases Mammosphere Formation following Treatment with P4

(A–C) Double immunostaining for GHR with PR (A and B) or ER (C) on normal mammary epithelium shows no colocalization of GHR with either of these markers.

(D) Mammosphere formation was increased by treatment with conditioned medium (CM) from previous culture treated with MPA, P4, or E2+MPA, compared to control (CM from nontreated culture, NT). The increased mammosphere formation was inhibited by PR antagonist RU486 or by GHA. No effect was observed when conditioned medium from E2 alone was used (three independent experiments on different patient samples, each performed in triplicate, n = 3).

(E) Mammosphere formation was increased by treatment with conditioned medium (CM) from previous culture treated with P4 or E2+P4, compared to control (CM(NT)). The increase in mammosphere formation was inhibited by GHA (representative example form three independent experiments on different patient samples, each performed in triplicate, n = 3)

(F) Mammosphere formation was increased upon treatment with conditioned medium from P4-treated cultures CM (P4) in cultures of primary mammary epithelial cells infected with nonsilencing shRNA, but not in cultures of GHR kd cells (representative example from three independent experiments in different mammoplasty samples, each performed in triplicates, n = 3).

Data are presented as means ± SD.